Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: source attribution (Rychlá Hypo, verified in bank calculators), the specific set of banks, and the ancillary data returned (LTV surcharges, limits, fees). Freshness/verification framing is useful but no caching or refresh cadence is given.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Effectively two sentences, front-loaded with what is returned and then source attribution. The parenthetical list of six banks is long but earns its place by telling the agent exactly which institutions are covered.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description must convey the return shape, and it does list the categories returned (rates by fixation, LTV surcharges, limits, fees) plus source. It stops short of describing the actual structure/fields, but is adequate for a single-optional-param read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the fixation enum is documented in the schema itself, including the unavailable/fixation_offered=false behavior. The description only adds 'by fixation period', so it neither needs to nor does add meaning beyond the schema; baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific resource (current published mortgage rates) and scope (6 named Czech banks, by fixation period) with the data's coverage (LTV surcharges, limits, fees). An agent can distinguish it from calculate_max_mortgage and compare_mortgages, which operate on rather than supply this data.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: this is the raw rates source, so an agent infers it should be called when benchmark rate data is needed. There is no explicit when-to-use, when-not, or pointer to compare_mortgages/calculate_max_mortgage as follow-ups or alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.